Where comes this "divide by two" rule from? Is this something related only
to 3590 drives?
For SCSI this cannot be true because there would be no way to have 5-6
disks on a bus with this "rate divide".

Zlatko Krastev
IT Consultant





"Cook, Dwight E (SAIC)" <cookde AT BP DOT COM> on 20.12.2001 17:55:54
Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
To:     ADSM-L AT VM.MARIST DOT EDU
cc:

Subject:        Re: SCSI Channel to LTO drive rule of thumb

Well, I can fill you in on 3590 drives and that might be close to LTO's

for each drive on the chain, add half of the previous drives thruput

with 3590-B1A's a single drive on a scsi card all by itself is rated at 9
MB/sec
add another one on the chain, you will gain another 4.5 MB/sec  (9/2)  or a
total of 13.5 MB/sec
add another one on the chain, you will gain another 2.25 MB/sec   (4.5/2)
or
a total of 15.75 MB/sec
add another one on the chain, you will gain another 1.125 MB/sec   (2.25/2)
or a total of  16.875 MB/sec

so you see, past two drives on a card, things get ugly fast...